Ignition device in a rocket assisted projectile

ABSTRACT

An ignition device for a rocket-assisted projectile to be fired from a gun comprises a detonator which when activated ignites a delay composition of a kind burning without flame and without generating hot gases, and a support for a composition of the type burning when activated non-explosively with a hot flame for a prolonged period of time. This support is movable by the centrifugal force acting upon it when the projectile is fired and spins, from a rest position to an active position in which the composition on the support is ignited by the heat of the burning delay composition. The burning of the composition on the support member in turn, ignites via an also non-explosively burning priming charge the propellant fuel of the rocket motor of the rocket-assisted projectile.

United States Patent [1 1 Hjelm 1 Jan. 30, 1973 IGNITION DEVICE IN A ROCKET- ASSISTED PROJECTILE Karl Erik Waldemar lljelm, Karlskoga, Sweden Aktiebolaget Bofors, Bofors, Sweden Oct. 12, 1970 Inventor:

[30] Foreign Application Priority Data US. Cl ..l02/49.7, [02/70 Int. Cl. ..F42b 19/08 Field of Search ..l02/49.7, 70

References Cited UNITED STATES PATENTS 3,119,303 1/1964 Jasse ..l02/49.7

Primary ExaminerVerlin R. Pendegrass Attorney-Heine, Baxley & Spiecens [57] ABSTRACT An ignition device for a rocket-assisted projectile to be fired from a gun comprises a detonator which when activated ignites a delay composition of a kind burning without flame and without generating hot gases, and a support for a composition of the type burning when activated non-explosively with a hot flame for a prolonged period of time. This support is movable by the centrifugal force acting upon it when the projectile is fired and spins, from a rest position to an active position in which the composition on the support is ignited bythe heat of the burning delay composition. The burning of the composition on the support member in turn, ignites via an also non-explosively burning priming charge the propellant fuel of the rocket motor of the rocket-assisted projectile.

7 Claims, 3 Drawing Figures y; Hie/5,1 1/41,;

PATENTED JAN 3 0 I975 INVENTOR.

MEL ERIK WALDEMR HJEZM- BY?! 160,44 w

ATTORNEYS IGNITION DEVICE IN A ROCKET-ASSISTED PROJECTILE The present invention relates to an ignition device for a rocket-assisted projectile, which when fired from a barrel or corresponding arrangement is given acceleration which causes both the releasing of an initiating unit and separation of a supporting part on which a flame-producing member is located. By rocket-assisted projectile is meant an artillery projectile which has been provided with an additional rocket motor in tended to increase the firing range of the projectile. The acceleration obtained at the firing as a rule consists of both a linear acceleration along the line of symmetry of the rocket-assisted projectile and a rotation-generating angular acceleration along the same line of symmetry. The ignition device is located at or in the motor of the rocket-assisted projectile.

The ignition device is to achieve reliable and explosion-free ignition of a propellent in the motor of the rocket-assisted projectile, e.g. in the form of powder, which ignition prevents the risks of damage to structural elements in the rocket-assisted projectile at the ignition. Further, the ignition device shall provide the possibility of, in a simple way, controlling in advance the time between the firing of the projectile from the artillery piece and the ignition of the rocket motor, as this time should have a certain relation to the burning time of the rocket motor, so that with the rocket assisted projectile an optimum firing range is obtained, at the same time as there shall be little dispersion of the impacts of different rocket-assisted projectiles.

In addition to this, it is an indispensable requirement for the ignition device that this is safe against accidental ignition of the motor of the rocket-assisted projectile during the transport and storage of the projectile.

The present invention solves all of the above-mentioned problems and is substantially characterized in that the initiating unit, when initiated, ignites a delay composition containing combustible material that burns without a flame and without hot gases, in that the supporting part, when displaced, achieves that the flame-producing member comes into contact with the delay composition which after a predetermined period of time through the heat conduction ignites the flameproducing member and in that the flame-producing member also consists of a substance that is arranged to burn non-explosively with a hot flame of long duration, the member being positioned in such a way that it, in turn, via an also non-explosively burning priming charge causes the ignition of the propellent in the motor of the rocket-assisted projectile.

An embodiment having the characteristics that are significant for the invention will be described in the following, with reference to the attached drawings, in which FIG. I in an elevational side view shows an ignition device in an unactuated condition;

FIG. 2 in a plan view shows a cross-section A-A of the ignition device according to FIG. 1;

FIG. 3 in an elevational side view shows the ignition device according to FIG. 1 in its actuated condition.

In the Figures, the parts corresponding to each other have been given the same reference designations. In FIG. I, the designation 1 shows a priming charge in the ignition device, which priming charge via apertures 2 in a part 3 encasing the charge is in contact with a propellent not shown in the motor of the rocket-assisted projectile. The priming charge is via a further aperture 4 in communication with a member 5. This member constitutes a safety and arming part 5, which is screwed into the part 3 encasing the charge I.

The safety and arming part 5 comprises an initiating unit 6 in the form of a detonator, which is movably arranged in a recess 7 where. In the unactuated condition of the rocket-assisted projectile detonator 6 is retained in one of its outer positions by a spring 8. As a consequence of the inertia of the detonator, the linear acceleration generated when the rocket-assisted projectile is fired from a barrel or corresponding arrangement causes the spring force of the spring 8 to be overcome, and the detonator is thrown against a striker point 9, so that it is activated. The recess 7 for the detonator is in communication with a delay composition 10 via a connection 11, which causes the detonator, when initiated,

to ignite the delay composition. This composition consis'ts of a combustible material that burns without flame and hot gases, and is also arranged in a column-formed recess so that the ignition of the delay composition takes place only at one end of it. In this embodiment, the combustible material contains zirconium-nickel, boron and barium-chromate.

The arming and safety part also includes a movably arranged supporting part 13 in a recess 12. Said recess 12 extends in the radial direction of the rocket-assisted projectile along an imaginary diameter, and from a central safety position (see FIG. 1) the supporting part 13 can be actuated to either one of two outer positions, one of which has been assumed in FIG. 3, by a centrifugal force caused by the rotation-generating angular acceleration of the rocket-assisted projectile. The central safety position is obtained by means of two plungers 14, which are also movably arranged, each in its recess, which also extend in the radial direction of the rocketassisted projectile, but at right angles to the direction of the recess 12. The plungers 14 are each provided with a shaft, and the shafts are, furthermore, inserted each in its recess on the movably arranged supporting part 13 when the rocket-assisted projectile is in its resting position, as the plungers are then each pressed by their spring 16 against said supporting part 13. When the centrifugal force occurs, the spring forces in the springs 16 are overcome, and the plungers are pressed outwards, which has the consequence that the shafts are withdrawn from the recesses of the supporting part 13, and that said part 13 is then actuated by the centrifugal force out towards one of its outer positions, for instance the outer position shown in FIG. 3.

The supporting part 13 also supports two flameproducing members in the form of powder pellets 17, one of which, when the supporting part 13 is in its outer position, comes into contact with the delay composition on the side thereof which is not ignited by the detonator. When the supporting part is in the outer position, the powder pellet is also connected with the priming charge 1 via the further channel 4.

When the delay composition 10 has burned down, the contact heat ignites the powder pellet non-explosively, and thereafter burns non-explosively with a hot flame of long duration, which flame ignites the also non-explosively burning priming charge which, in turn, ignites the propellent of the rocket-assisted projectile.

Due to the above-mentioned arrangement, the ignition device consists of a safety part and a priming part. The safety part contains both the safety and the arming functions, while the priming part contains the actual priming charge for the motor of the rocket-assisted projectile. Reliable, full ignition of the propellent of the rocket-assisted projectile can then be obtained by allowing the priming part to produce a strong flame of long duration. The priming part is also ignited in a nonexplosive way by a hot flame, which is of great importance from both the point of view of safety and from the point of view of the functioning of the rocketassisted projectile. Furthermore, the powder pellets 17 in the safety position are located so far from the gasless delay composition that it cannot be ignited by the heat from the delay composition if this composition should accidentally be ignited by the detonator. Furthermore, the burning time of the delay composition can be varied in a simple way by changing the height of the column-formed composition.

Moreover, the ignition device according to the present invention has been given such a design that one or several of its parts can easily be exchanged, or while in storage, for instance, can be temporarily removed.

The invention is not limited to the embodiment shown above, but can be subject to modifications within the scope of the following claims.

I claim:

1. An ignition device for igniting the propellant of a rocket-assisted projectile to which is imparted, on firing, linear and rotary acceleration, said ignition device comprises in combination:

priming means including a non-explosively burning priming charge for igniting a propellant for the rocket;

arming means including a control member movable between a neutral position and an active position and supporting a non-explosively burning first combustible composition which upon movement of said control member into its active position is in coacting relationship with said priming charge for igniting the same, a non-explosively burning second combustible composition positioned to be out of coacting relationship with said first composition when the control member is in its neutral position and in coacting relationship with the first composition when said control member is in its active position, and firing initiating means for igniting said second composition; and

safety means including first restraining means responsive to linear acceleration of the ignition device and coacting with said initiating means for retaining the same in a neutral position and releasing said means for movement into a position igniting the second composition in response to linear acceleration of the ignition device, and second restraining means responsive to rotational accelerationship of the ignition device for retaining said control member in its neutral position and releasing said member for movement into its active position to cause movement of said first composition into said coacting relationship with the priming charge upon rotational acceleration of the ignition device thereby effecting ignition of the priming charge via the initiating means, the second combustible composition and the first combustible composition. l 2. The ignition devlce according to claim 1 wherein said initiating means comprise a detonating composition in coacting relationship with said second combustible composition and a striker pin which, in response to a linear acceleration of the ignition device, impacts the detonating composition thereby causing detonation of the same.

3. The ignition device according to claim 1 comprising a casing member including a tubular recess, said second combustible composition being contained in said recess, one end of second composition being in a coacting relationship with said initiating means and the other end of said second composition being in coacting relationship with the first combustible composition when said control member is in its active position.

4. The ignition device according to claim 1 comprising a casing member including an elongate recess disposed transversely with reference to direction of the linear acceleration of the ignition device, said control member being lengthwise slidable in said recess between a central position and outer positions at either end of said elongate recess, the central position constituting the neutral position of the control member and either one of the outer positions constituting the active position of the control member, said control member moving into either one of its outer positions in response to the centrifugal force generated by rotational acceleration of the ignition device.

5. The ignition device according to claim 4 wherein said second restraining means comprise a recess in said control member, a lengthwise displaceable pin engagable with said recess when the control member is in its neutral position and spring means biasing said pin into engagement with said recess, said recess and said pin being disposed transversely with respect to the linear acceleration of the ignition device for causing withdrawal of the pin from the recess of the said restraining means in response to the centrifugal force generated by rotational acceleration of the ignition device thereby freeing the control member for movement from its neutral position toward either one of its outer positions.

6. The ignition device according to claim 5 wherein said elongate recess for the control member and said recess for receiving said pin therein are disposed normal to each other.

7. The ignition device according to claim 1 and comprising a casing body, said first restraining means including a recess extending in said casing body in the direction of the linear acceleration of the ignition device, a striker pin disposed at the inner end of said recess, said initiating means being slidably fitted in said recess, and a spring biasing the initiating means toward a position spaced apart from said striker pin, the inertia acting upon the initiating means when the ignition device is subjected to linear acceleration causes movement of said means toward and into engagement with said striker pin against the action of the spring means thereby activating the initiating means for the purpose aforesaid. 

1. An ignition device for igniting the propellant of a rocket-assisted projectile to which is imparted, on firing, linear and rotary acceleration, said ignition device comprises in combination: priming means including a non-explosively burning priming charge for igniting a propellant for the rocket; arming means including a control member movable between a neutral position and an active position and supporting a non-explosively burning first combustible composition which upon movement of said control member into its active position is in coacting relationship with said priming charge for igniting the same, a non-explosively burning second combustible composition positioned to be out of coacting relationship with said first composition when the control member is in its neutral position and in coacting relationship with the first composition when said control member is in its active position, and firing initiating means for igniting said second composition; and safety means including first restraining means responsive to linear acceleration of the ignition device and coacting with said initiating means for retaining the same in a neutral position and releasing said means for movement into a position igniting the second composition in response to linear acceleration of the ignition device, and second restraining means responsive to rotational accelerationship of the ignition device for retaining said control member in its neutral position and releasing said member for movement into its active position to cause movement of said first composition into said coacting relationship with the priming charge upon rotational acceleration of the ignition device thereby effecting ignition of the priming charge via the initiating means, the second combustible composition and the first combustible composition.
 1. An ignition device for igniting the propellant of a rocketassisted projectile to which is imparted, on firing, linear and rotary acceleration, said ignition device comprises in combination: priming means including a non-explosively burning priming charge for igniting a propellant for the rocket; arming means including a control member movable between a neutral position and an active position and supporting a nonexplosively burning first combustible composition which upon movement of said control member into its active position is in coacting relationship with said priming charge for igniting the same, a non-explosively burning second combustible composition positioned to be out of coacting relationship with said first composition when the control member is in its neutral position and in coacting relationship with the first composition when said control member is in its active position, and firing initiating means for igniting said second composition; and safety means including first restraining means responsive to linear acceleration of the ignition device and coacting with said initiating means for retaining the same in a neutral position and releasing said means for movement into a position igniting the second composition in response to linear acceleration of the ignition device, and second restraining means responsive to rotational accelerationship of the ignition device for retaining said control member in its neutral position and releasing said member for movement into its active position to cause movement of said first composition into said coacting relationship with the priming charge upon rotational acceleration of the ignition device thereby effecting ignition of the priming charge via the initiating means, the second combustible composition and the first combustible composition.
 2. The ignition device according to claim 1 wherein said initiating means comprise a detonating composition in coacting relationship with said second combustible composition and a striker pin which, in response to a linear acceleration of the ignition device, impacts the detonating composition thereby causing detonation of the same.
 3. The ignition device according to claim 1 comprising a casing member including a tubular recess, said second combustible composition being contained in said recess, one end of second composition being in a coacting relationship with said initiating means and the other end of said second composition being in coacting relationship with the first combustIble composition when said control member is in its active position.
 4. The ignition device according to claim 1 comprising a casing member including an elongate recess disposed transversely with reference to direction of the linear acceleration of the ignition device, said control member being lengthwise slidable in said recess between a central position and outer positions at either end of said elongate recess, the central position constituting the neutral position of the control member and either one of the outer positions constituting the active position of the control member, said control member moving into either one of its outer positions in response to the centrifugal force generated by rotational acceleration of the ignition device.
 5. The ignition device according to claim 4 wherein said second restraining means comprise a recess in said control member, a lengthwise displaceable pin engagable with said recess when the control member is in its neutral position and spring means biasing said pin into engagement with said recess, said recess and said pin being disposed transversely with respect to the linear acceleration of the ignition device for causing withdrawal of the pin from the recess of the said restraining means in response to the centrifugal force generated by rotational acceleration of the ignition device thereby freeing the control member for movement from its neutral position toward either one of its outer positions.
 6. The ignition device according to claim 5 wherein said elongate recess for the control member and said recess for receiving said pin therein are disposed normal to each other. 